The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
John S. Clayton - One of the best experts on this subject based on the ideXlab platform.
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Native flora and fauna response to removal of the weed Hydrilla verticillata (L.f.) Royle in Lake Tutira
Hydrobiologia, 2014Co-Authors: Deborah Hofstra, John S. ClaytonAbstract:Hydrilla has been in New Zealand since the 1960s and formed major infestations in four lakes in the Hawkes Bay region. Challenges to controlling Hydrilla in New Zealand have included a lack of tools and the changing responsibilities of local management agencies. A grass carp field trial was initiated in 1988 in the smallest of the Hydrilla infested lakes to assess the feasibility of eradicating Hydrilla. After the main Hydrilla beds were consumed, regrowth from tubers still occurred for a further 12 years. In 2008, grass carp were released into the remaining three Hydrilla-infested lakes in a central government led response to eradicate Hydrilla. This paper describes the changes in the flora and fauna in the largest of these lakes, Lake Tutira, following the introduction of grass carp and the removal of the Hydrilla weed beds. Annual surveys of aquatic vegetation and macroinvertebrates in the lake from 2008 to 2012 have shown that, following the removal of the Hydrilla weed beds by 2010, there was a shift in grass carp grazing to marginal emergent plants, and a general increase in the distribution of the native plant vegetation, although there was some evidence of a decline in charophyte abundance. Macroinvertebrate diversity was maintained although there were changes in the relative abundance of taxa linked to changes in the littoral vegetation.
Franck E Dayan - One of the best experts on this subject based on the ideXlab platform.
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somatic mutation mediated evolution of herbicide resistance in the nonindigenous invasive plant Hydrilla Hydrilla verticillata
Molecular Ecology, 2004Co-Authors: Albrecht Michel, Brian E Scheffler, M D Netherland, Stephen O Duke, Renee S. Arias, Franck E DayanAbstract:Hydrilla ( Hydrilla verticillata L.f. Royle) was introduced to the surface water of Florida in the 1950s and is today one of the most serious aquatic weed problems in the USA. As a result of concerns associated with the applications of pesticides to aquatic systems, fluridone is the only USEPA-approved chemical that provides systemic control of Hydrilla. After a decrease in fluridone’s efficacy at controlling Hydrilla, 200 Florida water bodies were sampled to determine the extent of the problem and the biological basis for the reduced efficacy. Our studies revealed that Hydrilla phenotypes with two- to six-fold higher fluridone resistance were present in 20 water bodies. Since fluridone is an inhibitor of the enzyme phytoene desaturase (PDS), the gene for PDS ( pds ) was cloned from herbicidesusceptible and -resistant Hydrilla plants. We report for the first time in higher plants three independent herbicide-resistant Hydrilla biotypes arising from the selection of somatic mutations at the arginine 304 codon of pds . The three PDS variants had specific activities similar to the wild-type enzyme but were two to five times less sensitive to fluridone. In vitro activity levels of the enzymes correlated with in vivo resistance of the corresponding biotypes. As Hydrilla spread rapidly to lakes across the southern United States in the past, the expansion of resistant biotypes is likely to pose significant environmental challenges in the future.
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Somatic mutation-mediated evolution of herbicideresistance in the nonindigenous invasive plant Hydrilla( Hydrilla verticillata )And Franck E. Dayan
2004Co-Authors: Albrecht Michel, Brian E Scheffler, M D Netherland, Stephen O Duke, Renee S. Arias, Franck E DayanAbstract:Hydrilla ( Hydrilla verticillata L.f. Royle) was introduced to the surface water of Florida in the 1950s and is today one of the most serious aquatic weed problems in the USA. As a result of concerns associated with the applications of pesticides to aquatic systems, fluridone is the only USEPA-approved chemical that provides systemic control of Hydrilla. After a decrease in fluridone’s efficacy at controlling Hydrilla, 200 Florida water bodies were sampled to determine the extent of the problem and the biological basis for the reduced efficacy. Our studies revealed that Hydrilla phenotypes with twoto six-fold higher fluridone resistance were present in 20 water bodies. Since fluridone is an inhibitor of the enzyme phytoene desaturase (PDS), the gene for PDS ( pds ) was cloned from herbicidesusceptible and -resistant Hydrilla plants. We report for the first time in higher plants three independent herbicide-resistant Hydrilla biotypes arising from the selection of somatic mutations at the arginine 304 codon of pds . The three PDS variants had specific activities similar to the wild-type enzyme but were two to five times less sensitive to fluridone. In vitro activity levels of the enzymes correlated with in vivo resistance of the corresponding biotypes. As Hydrilla spread rapidly to lakes across the southern United States in the past, the expansion of resistant biotypes is likely to pose significant environmental challenges in the future.
James P Cuda - One of the best experts on this subject based on the ideXlab platform.
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Influence of competition and predation on survival of the Hydrilla tip mining midge and its success as a potential augmentative biological control agent of Hydrilla
Hydrobiologia, 2020Co-Authors: Courtney Stachowiak, James P Cuda, Julie Baniszewski, Colette St. Mary, Emma N I WeeksAbstract:Hydrilla verticillata is an aquatic weed that grows densely throughout the water column and is costly to manage. The Hydrilla tip mining midge, Cricotopus lebetis , a potential augmentative biological control agent of Hydrilla, feeds on the apical meristem preventing growth. The goal of this study was to quantify the influence of a predator (mosquitofish, Gambusia sp.) and a competitor (Hydrilla leafcutter moth, Parapoynx diminutalis ) and their interactions, on the ability of the midge to survive and feed on Hydrilla. The first experiment involved six treatments established in 37.8 L tanks with combinations of the organisms, including larval C. lebetis . Survival to adult midge eclosion was significantly reduced in the presence of the predator but was unaffected by the competitor’s presence alone. Apical meristem damage was reduced when both the competitor and predator were present. The second experiment included four treatments with C. lebetis egg masses or larvae and the presence or absence of mosquitofish. Adding C. lebetis as eggs rather than as larvae increased midge survival in the absence of the predator. Midge survival was lower when larvae were added, but the predator had no additional effect. To facilitate successful establishment of the midge and control of Hydrilla, high numbers of larvae should be released to overcome predation.
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cricotopus lebetis intraspecific competition and damage to Hydrilla
Florida Entomologist, 2020Co-Authors: Julie Baniszewski, James P Cuda, Nicole Miller, Eutychus M Kariuki, Emma N I WeeksAbstract:Cricotopus lebetis Sublette (Diptera: Chironomidae) is an aquatic insect adventive in Florida. Evidence from previous studies suggest the insect may have value as an augmentative biological control agent for Hydrilla, Hydrilla verticillata (L.f.) Royle (Hydrocharitaceae), but there are gaps in knowledge of the biology and life history traits. To increase understanding of this insect, this study was comprised of 3 experiments. In the first experiment, we investigated the productivity and survival rate of C. lebetis across 6 generations by analyzing our colony data. Then the effect of intraspecific competition on the rates of pupal and adult eclosion was studied by monitoring Hydrilla tips in test tubes with varying numbers of larvae. Finally, the level of Hydrilla stem tip damage caused by a C. lebetis larva was determined by monitoring tip damage following feeding of a known number of larvae on a standardized number of Hydrilla tips. The first experiment revealed the average survival rate of C. lebetis from egg to adult was 16.4%. Approximately a third of the females (30.2%) oviposited. The egg masses had an average of 154.5 eggs per egg mass and an 83.7% fertility rate. Investigation of intraspecific competition revealed pupation and adult eclosion was highest with 1 C. lebetis larva per Hydrilla stem tip. Evaluation of the impact of C. lebetis larvae feeding on Hydrilla showed stem tips in treatments with C. lebetis larvae experienced 38% higher damage compared to stem tips in control treatments. Overall, this study provided valuable information useful in improving the mass rearing of C. lebetis and predicting the damage caused by C. lebetis. For example, for efficient mass rearing, an average of 1 larva per Hydrilla tip should be maintained with the remainder of eggs being used for augmentative releases.
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Effect of food deprivation on Hydrilla tip mining midge survival and subsequent development
Florida Entomologist, 2018Co-Authors: Adriana O. Mitchell, James P Cuda, Alissa Berro, Emma N I WeeksAbstract:Hydrilla, Hydrilla verticillata (L.f.) Royle (Hydrocharitaceae), is an invasive aquatic macrophyte found in fresh water. The introduction of Hydrilla by the aquarium plant trade has led to its invasion throughout much of the southern US and its current listing as a federal noxious weed. Hydrilla employs many pathways of reproduction and once established can rapidly fill the water column, impeding recreation and negatively affecting the environment. Waterways infested with Hydrilla typically experience matting of vegetation at the surface that results in less light penetration, and changes in dissolved oxygen levels, which disturb native species richness and diversity. Efforts to minimize Hydrilla populations include using biological control agents such as the Hydrilla tip mining midge, Cricotopus lebetis Sublette (Diptera: Chironomidae). The larvae of C. lebetis feed on the apical meristem of Hydrilla tips, disabling further vertical growth and forcing growth into a branched horizontal direction. Currently, a colony of C. lebetis is being mass-reared to augment midge populations throughout Hydrilla-infested waters. In order to maintain colony viability for effective releases, midge eggs must be collected and placed on Hydrilla before larvae exhaust endogenous nutrient reserves. To understand the effects of larval starvation on survival and subsequent development to adult eclosion, neonates at 0, 1, 2, and 3 d post-hatch were studied with and without access to food. Midge survival and adult eclosion decreased significantly after continued starvation post-hatch. Larvae starved for 2 d post-hatch did not eclose. Highest survival to adult eclosion occurred when midge larvae were placed on Hydrilla as soon as they hatched (48 h post-oviposition). This study highlights fundamental information necessary for efficient midge rearing for effective biological control of Hydrilla.
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bacillus thuringiensis subspecies kurstaki reduces competition by parapoynx diminutalis lepidoptera crambidae in colonies of the Hydrilla biological control agent cricotopus lebetis diptera chironomidae
Florida Entomologist, 2016Co-Authors: Julie Baniszewski, Emma N I Weeks, James P CudaAbstract:Abstract The Hydrilla tip mining midge, Cricotopus lebetis Sublette (Diptera: Chironomidae), is a biological control agent of the invasive aquatic weed Hydrilla, Hydrilla verticillata (L.f.) Royle (Hydrocharitaceae). Mass rearing of the midge for augmentative releases can be compromised by competition from the adventive Hydrilla leafcutter moth, Parapoynx diminutalis Snellen (Lepidoptera: Crambidae). The objective of this study was to evaluate the biorational pesticide Bacillus thuringiensis (subspecies kurstaki) (Btk) for reducing competition by the moth in laboratory colonies of the Hydrilla tip mining midge. Dose response bioassays with Btk were completed with both species to determine the minimum concentration that kills the moth without affecting midge production. Adult moth emergence was significantly reduced at concentrations of 2.0 mL Btk per 3.8 L of well water. A concentration of 0.2 mL Btk per 3.8 L of well water also reduced the number of emerging moths by 50%. However, midge development decli...
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CHIRONOMIDAE (INSECTA: DIPTERA) COLLECTED FROM Hydrilla VERTICILLATA (HYDROCHARITACEAE) AND OTHER SUBMERSED AQUATIC MACROPHYTES IN LAKE BISINA AND OTHER UGANDAN LAKES
Journal of East African Natural History, 2012Co-Authors: Robert S. Copeland, James P Cuda, John H. Epler, Brian Gidudu, Fred Wanda, William A. OverholtAbstract:ABSTRACT A survey of the aquatic weed Hydrilla verticillata was conducted in selected Kenyan and Ugandan lakes, and emerging chironomid adults were collected from samples of Hydrilla and seven other aquatic macrophytes. Hydrilla was absent from Lake Victoria, in sites where it previously occurred. Hydrilla was found in four of nine lakes examined in Uganda, i.e. Bisina, Kyoga, Bunyonyi and Mutanda. From 7424 collected chironomid adults, 43 species were identified, 21 (49%) representing new Ugandan records. Thirty-nine (91%) of the species were found on Hydrilla. Three species represent probable undescribed taxa. At our primary site, Lake Bisina, the genera Tanytarsus and Dicrotendipes dominated the chironomid community, comprising 76% of emerged adults. A species accumulation curve for chironomid species associated with Lake Bisina macrophytes suggested that further plant sampling would uncover additional species. Polypedilum wittei, formerly considered for possible biological control of Hydrilla, was not...
W. T. Z. Sousa - One of the best experts on this subject based on the ideXlab platform.
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Hydrilla verticillata (Hydrocharitaceae), a recent invader threatening Brazil’s freshwater environments: a review of the extent of the problem
Hydrobiologia, 2011Co-Authors: W. T. Z. SousaAbstract:Hydrilla verticillata (Hydrocharitaceae) is a highly prolific, rooted submerged macrophyte native to Asia that has invaded aquatic systems worldwide, causing many ecological and human-related problems. Hydrilla recently invaded the Paraná River basin in Brazil, making other ecologically and socially important Brazilian watersheds more susceptible to invasion by this plant. Here, I summarize the relevant information about Hydrilla , focusing on its biotic attributes, abiotic tolerance and effects on ecosystems. The aim of this review is to provide background information to assist with planning for the potential impacts of this species in the Neotropical region (particularly in Brazil) and the development of research, monitoring and management strategies. A wide ecological amplitude, resistance organs, and high growth rates and dispersion ability provide Hydrilla with great potential to invade and infest a variety of habitats, often resulting in important physico-chemical and biotic effects on the environment. Hydrilla is similar in its morphological and ecological aspects to Egeria najas and Egeria densa (South American Hydrocharitaceae), but this non-native species is a superior competitor and can be expected to exert significant pressure in habitats colonized by these native Hydrocharitaceae. Socially important rivers (such as the São Francisco River) have a high risk of being infested with Hydrilla , especially in stretches affected by dams, which could prejudice important human activities like hydropower generation. Important wetlands for biodiversity conservation (such as the Pantanal) may also be invaded, but they seem to be more resistant to infestations as long as their natural hydrologies are preserved. Before investing substantial effort to control Hydrilla , managers should weigh the potential costs and benefits of available techniques and consider the potential benefits of Hydrilla in providing ecosystem services.
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Hydrilla verticillata hydrocharitaceae a recent invader threatening brazil s freshwater environments a review of the extent of the problem
Hydrobiologia, 2011Co-Authors: W. T. Z. SousaAbstract:Hydrilla verticillata (Hydrocharitaceae) is a highly prolific, rooted submerged macrophyte native to Asia that has invaded aquatic systems worldwide, causing many ecological and human-related problems. Hydrilla recently invaded the Parana River basin in Brazil, making other ecologically and socially important Brazilian watersheds more susceptible to invasion by this plant. Here, I summarize the relevant information about Hydrilla, focusing on its biotic attributes, abiotic tolerance and effects on ecosystems. The aim of this review is to provide background information to assist with planning for the potential impacts of this species in the Neotropical region (particularly in Brazil) and the development of research, monitoring and management strategies. A wide ecological amplitude, resistance organs, and high growth rates and dispersion ability provide Hydrilla with great potential to invade and infest a variety of habitats, often resulting in important physico-chemical and biotic effects on the environment. Hydrilla is similar in its morphological and ecological aspects to Egeria najas and Egeria densa (South American Hydrocharitaceae), but this non-native species is a superior competitor and can be expected to exert significant pressure in habitats colonized by these native Hydrocharitaceae. Socially important rivers (such as the Sao Francisco River) have a high risk of being infested with Hydrilla, especially in stretches affected by dams, which could prejudice important human activities like hydropower generation. Important wetlands for biodiversity conservation (such as the Pantanal) may also be invaded, but they seem to be more resistant to infestations as long as their natural hydrologies are preserved. Before investing substantial effort to control Hydrilla, managers should weigh the potential costs and benefits of available techniques and consider the potential benefits of Hydrilla in providing ecosystem services.
Susan B Wilde - One of the best experts on this subject based on the ideXlab platform.
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Vacuolar myelinopathy: waterbird risk on a southeastern impoundment co-infested with Hydrilla verticillata and Aetokthonos hydrillicola
Biological Invasions, 2020Co-Authors: Brigette N. Haram, Susan B Wilde, Michael J. Chamberlain, Kenneth H. BoydAbstract:Invasive aquatic plants such as Hydrilla ( Hydrilla verticillata ) are spreading through North America, impeding navigation and hydropower facilities, reducing macrophyte biodiversity, and affecting wildlife health. Managing invasive plants is challenging, especially when the scope of effects to aquatic ecosystems is not fully understood. Hydrilla supports a novel epiphytic cyanobacterium ( Aetokthonos hydrillicola ) which is implicated in vacuolar myelinopathy (VM) disease. Ingestion of aquatic plants with A. hydrillicola causes often fatal neurological impairment to waterbirds and is transferred from herbivore to predator. We investigated potential VM risk to wildlife species using Hydrilla infested sites at a southeastern reservoir and developed a qualitative risk assessment for waterbird species that inhabited the reservoir during fall and early winter. We found that all avian species we observed on the reservoir used Hydrilla beds to forage. Seasonal diets of these species exposed them to A. hydrillicola toxin either directly through herbivory, or indirectly through prey with dietary links to Hydrilla and the cyanobacteria. Avian and mammalian scavengers are also exposed to the toxin through waterbird carcasses. We present evidence that the current list of species affected by VM is not complete, and further studies are needed to determine the full scope of species vulnerable to VM in lakes and reservoirs with Hydrilla and A. hydrillicola .
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Spatiotemporal monitoring of Hydrilla [Hydrilla verticillata (L. f.) Royle] to aid management actions
Weed Technology, 2019Co-Authors: Abhishek Kumar, Christopher Cooper, Caren Remillard, Shuvankar Ghosh, Austin Haney, Frank Braun, Zachary Conner, Benjamin P. Page, Kenneth H. Boyd, Susan B WildeAbstract:Hydrilla is an invasive aquatic plant that has rapidly spread through many inland water bodies across the globe by outcompeting native aquatic plants. The negative impacts of Hydrilla invasion have become a concern for water resource management authorities, power companies, and environmental scientists. The early detection of Hydrilla infestation is very important to reduce the costs associated with control and removal efforts of this invasive species. Therefore, in this study, we aimed to develop a tool for rapid, frequent, and large-scale monitoring and predicting spatial extent of Hydrilla habitat. This was achieved by integrating in situ and Landsat 8 Operational Land Imager satellite data for Lake J. Strom Thurmond, the largest US Army Corps of Engineers lake east of the Mississippi River, located on the border of Georgia and South Carolina border. The predictive model for presence of Hydrilla incorporated radiometric and physical measurements, including remote-sensing reflectance, Secchi disk depth (SDD), light-attenuation coefficient (Kd), maximum depth of colonization (Zc), and percentage of light available through the water column (PLW). The model-predicted ideal habitat for Hydrilla featured high SDD, Zc, and PLW values, low values of Kd. Monthly analyses based on satellite images showed that Hydrilla starts growing in April, reaches peak coverage around October, begins retreating in the following months, and disappears in February. Analysis of physical and meteorological factors (i.e., water temperature, surface runoff, net inflow, precipitation) revealed that these parameters are closely associated with Hydrilla extent. Management agencies can use these results not only to plan removal efforts but also to evaluate and adapt their current mitigation efforts.Nomenclature:Hydrilla; Hydrilla verticillata (L. f.) Royle
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experimental feeding of Hydrilla verticillata colonized by stigonematales cyanobacteria induces vacuolar myelinopathy in painted turtles chrysemys picta
PLOS ONE, 2014Co-Authors: Albert D Mercurio, Sonia M Hernandez, John C Maerz, Michael J Yabsley, Angela E Ellis, Amanda L Coleman, Leslie M Shelnutt, John R Fischer, Susan B WildeAbstract:Vacuolar myelinopathy (VM) is a neurologic disease primarily found in birds that occurs when wildlife ingest submerged aquatic vegetation colonized by an uncharacterized toxin-producing cyanobacterium (hereafter “UCB” for “uncharacterized cyanobacterium”). Turtles are among the closest extant relatives of birds and many species directly and/or indirectly consume aquatic vegetation. However, it is unknown whether turtles can develop VM. We conducted a feeding trial to determine whether painted turtles (Chrysemys picta) would develop VM after feeding on Hydrilla (Hydrilla verticillata), colonized by the UCB (Hydrilla is the most common “host” of UCB). We hypothesized turtles fed Hydrilla colonized by the UCB would exhibit neurologic impairment and vacuolation of nervous tissues, whereas turtles fed Hydrilla free of the UCB would not. The ability of Hydrilla colonized by the UCB to cause VM (hereafter, “toxicity”) was verified by feeding it to domestic chickens (Gallus gallus domesticus) or necropsy of field collected American coots (Fulica americana) captured at the site of Hydrilla collections. We randomly assigned ten wild-caught turtles into toxic or non-toxic Hydrilla feeding groups and delivered the diets for up to 97 days. Between days 82 and 89, all turtles fed toxic Hydrilla displayed physical and/or neurologic impairment. Histologic examination of the brain and spinal cord revealed vacuolations in all treatment turtles. None of the control turtles exhibited neurologic impairment or had detectable brain or spinal cord vacuolations. This is the first evidence that freshwater turtles can become neurologically impaired and develop vacuolations after consuming toxic Hydrilla colonized with the UCB. The southeastern United States, where outbreaks of VM occur regularly and where vegetation colonized by the UCB is common, is also a global hotspot of freshwater turtle diversity. Our results suggest that further investigations into the effect of the putative UCB toxin on wild turtles in situ are warranted.
